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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-453823ad247sm197230345e9.26.2025.07.01.03.12.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Jul 2025 03:12:28 -0700 (PDT) Message-ID: <1c7a557f-2ab4-465c-a84a-43dffbf4e0f4@linaro.org> Date: Tue, 1 Jul 2025 12:12:27 +0200 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 04/26] target/arm/hvf: Simplify GIC hvf_arch_init_vcpu() To: Peter Maydell Cc: qemu-devel@nongnu.org, Leif Lindholm , qemu-arm@nongnu.org, =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Roman Bolshakov , Paolo Bonzini , Alexander Graf , Bernhard Beschow , John Snow , Thomas Huth , =?UTF-8?Q?Marc-Andr=C3=A9_Lureau?= , kvm@vger.kernel.org, Eric Auger , Cameron Esfahani , Cleber Rosa , Radoslaw Biernacki , Phil Dennis-Jordan , Richard Henderson , =?UTF-8?Q?Alex_Benn=C3=A9e?= References: <20250623121845.7214-1-philmd@linaro.org> <20250623121845.7214-5-philmd@linaro.org> Content-Language: en-US From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/7/25 11:39, Peter Maydell wrote: > On Mon, 23 Jun 2025 at 13:19, Philippe Mathieu-Daudé wrote: >> >> Only update the ID_AA64PFR0_EL1 register when a GIC is provided. >> >> Signed-off-by: Philippe Mathieu-Daudé >> Reviewed-by: Richard Henderson >> --- >> target/arm/hvf/hvf.c | 14 +++++++++----- >> 1 file changed, 9 insertions(+), 5 deletions(-) >> >> diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c >> index 42258cc2d88..c1ed8b510db 100644 >> --- a/target/arm/hvf/hvf.c >> +++ b/target/arm/hvf/hvf.c >> @@ -1057,11 +1057,15 @@ int hvf_arch_init_vcpu(CPUState *cpu) >> arm_cpu->mp_affinity); >> assert_hvf_ok(ret); >> >> - ret = hv_vcpu_get_sys_reg(cpu->accel->fd, HV_SYS_REG_ID_AA64PFR0_EL1, &pfr); >> - assert_hvf_ok(ret); >> - pfr |= env->gicv3state ? (1 << 24) : 0; >> - ret = hv_vcpu_set_sys_reg(cpu->accel->fd, HV_SYS_REG_ID_AA64PFR0_EL1, pfr); >> - assert_hvf_ok(ret); >> + if (env->gicv3state) { >> + ret = hv_vcpu_get_sys_reg(cpu->accel->fd, >> + HV_SYS_REG_ID_AA64PFR0_EL1, &pfr); >> + assert_hvf_ok(ret); >> + pfr = FIELD_DP64(pfr, ID_AA64PFR0, GIC, 1); >> + ret = hv_vcpu_set_sys_reg(cpu->accel->fd, >> + HV_SYS_REG_ID_AA64PFR0_EL1, pfr); >> + assert_hvf_ok(ret); >> + } > > This doesn't seem like a simplification to me... > > Looking at the code, I suspect what we should really be doing > is setting the GIC field to either 0 or 1 depending on whether > env->gicv3state. Currently if hvf hands us an initial value with > the GIC field set to 1 but we don't have a gicv3state we won't > correctly clear it to 0. i.e. we should change the current > pfr |= env->gicv3state ? (1 << 24) : 0; > to > pfr = FIELD_DP64(pfr, ID_AA64PFR0, GIC, env->gicv3state ? 1 : 0); Good idea.